1. Field of the Invention
The present invention relates generally to a power charging method and apparatus, and more particularly to a method and apparatus for wirelessly charging power.
2. Description of the Related Art
Wireless charging technology is used to wirelessly supply and demand power without any connector for power transfer. The wireless charging technology is classified into an electromagnetic induction type using a coil, a wireless power transmission type converting an electric energy into a microwave to transfer the power, a type using resonance, and the like. The electromagnetic induction type power charging technology has conventionally been the mainstream, but recently, experiments in which the power is wirelessly transmitted within several tens of meters using microwaves have been successful at home and abroad. Thus, it is expected that an environment in which all electronic devices can be wirelessly charged anywhere and anytime will be realized in the near future.
The electromagnetic induction type transmits the power between a primary coil and a secondary coil using a property in that current is induced through movement of a magnet against a coil to generate the electricity. That is, a transmitting end generates a magnetic field, and a receiving end serves as a magnet to produce energy. This phenomenon is called magnetic induction. Since the electromagnetic induction type has excellent energy transmission efficiency, it has been widely commercialized, and applied to diverse devices such as electric shavers and electric toothbrushes, using nickel batteries.
The resonance type uses the resonance characteristics of an electromagnetic wave. Since this resonating electromagnetic wave is directly transferred only when a device having the resonance frequency exists and a portion that is not in use is reabsorbed into the electromagnetic field instead of spreading in the air, it is expected that the resonating electromagnetic wave will exert no influence on surrounding machines or human bodies, unlike other electromagnetic waves. The resonance type was previewed by a Massachusetts Institute of Technology (MIT) research team in 2005.
An RF/microwave radiation type is a power transmission type that transfers energy through a conversion of the power energy into a microwave that is favorable to the wireless transmission. The power transmission is to transmit the electric energy rather than a signal that is used in a wireless communication type such as a radio receiver, a wireless phone, or the like. That is, whereas a typical communication is to transmit a signal that is carried on a carrier signal, the wireless power transmission transmits only the carrier.
The wireless charging technology has been applied to wireless electric toothbrushes or wireless shavers. Also, a charging system which can automatically charge a battery that is put on a charging pad without connecting a separate charging connector to a portable phone may be exemplified. Such a wireless charging technology can heighten the waterproof function by wirelessly charging the electronic device, and heighten the portability of the electronic device since it does not require a wired charger.
A wireless charging system to which the above-described wireless charging technology is applied is provided with a power supply stand from which the power is supplied to a terminal. Thus, it has the disadvantage that the wireless charging becomes possible only in a location where the power supply stand is provided.